Occurrence and ecology of Armillaria species in virgin forests of the Ukrainian Carpathians

Background

Ukrainian Carpathians

Sampling Armillaria rhizomorphs

In the laboratory

Armillaria species

Over 40 Armillaria species are known worldwide, with seven of them occurring in Europe: A. gallica, A. cepistipes, A. ostoyae, A. borealis, A. mellea, A. tabescens, and A. ectypa. Armillaria species differ in geographical distribution, as well as in ecological behavior. As facultative saprotrophs, Armillaria species contribute significantly to wood decomposition. Moreover, some members of the genus are primary or secondary necrotrophic parasites, causing root and butt rot on a wide range of coniferous and broadleaved tree species.

The occurrence and ecology of Armillaria species have been well investigated in managed forest stands of western, southern, and south-eastern Europe. By contrast, only few detailed information is available for eastern European regions. In addition, since most European forest stands have been managed for centuries, very little is known about diversity, ecology, and distribution of Armillaria species in natural, undisturbed forest ecosystems in temperate Europe.

Objectives

The goal of this project is to characterize the large-scale occurrence of Armillaria species in two virgin forest massifs (pure beech massif, 14’600 ha; conifer/mixed forests massif, 15’000 ha) of the Carpathian Biosphere Reserve in south-western Ukraine. Specifically, we aim to:

1. quantify the presence of Armillaria rhizomorphs in the soil and on the root surface of trees (epiphytic rhizomorphs);
2. assess the impact of vegetation type, soil pH, and altitude on the occurrence of Armillaria rhizomorphs;
3. determine the composition of the Armillaria species community;
4. analyze the genetic population structure of the most frequent Armillaria species.

Methods

Sampling
In both forest massifs, Armillaria rhizomorphs will be systematically sampled on the 79 plots of the 1.5 km x 1.5 km square grid of the large-scale inventory. In each plot, a 20 m x 25 m (500 m²) rectangle will be established and sampling will be conducted by taking a cube of soil (15 cm side) at all four corners of the rectangle. In addition, the root collar of the nearest tree to each soil sampling point will be inspected for epiphytic rhizomorphs.

Laboratory analyses
Armillaria species will be identified by conducting classic interfertility tests with haploid testers of the five European annulated species (“Buller tests”), as well as with sequencing of the IGS-1 and ITS regions of the rDNA, and PCR-RFLP analysis of a portion of the IGS-1 and of the translational elongation factor 1-α gene region of the nuclear DNA. Genetic population structure of the most frequent Armillaria species will be analyzed using polymorphic microsatellite markers.

Partners

• Uzhgorod National University, Ukraine (Tetyana Tsykun)
• WSL (Simone Prospero, Daniel Rigling)
  
  

Publications

1. Tsykun T., Rigling D., Nikolaychuk V. (2008) New Armillaria species for Ukrainian Carpathians. Scientific Bulletin of the Uzhgorod University. Issue 22, pp. 73-79.
2. Tsykun T., Prospero S., Rigling D. (2009) Armillaria spp. in virgin beech forests in the Ukraine. Abstract book of posters of the 2009 annual meeting of the Swiss Zoological, Botanic, Mycological and Systematics Societies, p. 27.
3. Prospero S., Jung E., Tsykun T., Rigling D. (2010) Eight microsatellite markers for Armillaria cepistipes and their transferability to other Armillaria species. European Journal of Plant Pathology 127: 165–170
4. Tsykun T, Rigling D, Nikolaychuk V, Prospero S. Occurrence and ecology of Armillaria species in virgin forests of the Ukrainian Carpathians (submitted)
   
   

Contact

• Simone Prospero